Sliding-wndow and change-detection implementation

[raul-singh]

Here is my code for the dynamic learner. This is a normal simulation with an abrupt change at day 30 with a normal AlphalessLearner:

This instead is the same exact simulation (abrupt change at day 30) using a ChangeDetectionLearner:

This should be ready to go. Also sliding window is implemented:

I'm trying to write a notebook to show the differences between normal alphaless learner, sliding-window and change-detection.

[raul-singh]

I tried to implement most of your suggestions! Let me know what you think.